1. Field of the Invention
The invention relates to a device for urinalysis and in particular for the examination of urinary sediments.
2. Description of the Prior Art
In order to detect pathological processes in the urinary tract and to diagnose them in the early stages, so-called sediment analysis has been carried out for a long time. This principally involves microscopically detecting and evaluating pathological constituents from the urinary sediment, in order to be able to take appropriate therapeutic measures.
Erythrocytes and leukocytes are present in very small quantities in the urine of healthy subjects. An increase in these blood cells above experimentally determined limit values then provides an indication of inflammatory processes or other disorders. However, other cell types may also additionally be present in the urine, for example renal epithelial cells, urothelial cells of various types and also, in the urine from females, squamous epithelia. There are also casts, crystals, bacteria and others. Since these constituents are present in a varying liquid volume depending on the concentration, a drop of urine taken directly from a total specimen does not provide any quantifiable result under the microscope because, in general, the dilution factor is too high. A quantitative statement in addition to a morphological examination is only possible if an accumulation of the particles in the liquid takes place. A calculation of the number of the particular cells per ml of urine is only possible if the accumulation or concentration takes place exact and standardized.
For such an accumulation, a centrifugation has hitherto been used with, for example, 10 ml of urine being centrifuged at 2,000 g. A supernatant of 9 ml is then decanted off and the sediment is resuspended in 1 ml of residual urine. This suspension is then filled into a counting chamber, for example a Fuchs-Rosenthal chamber, which holds a defined amount of liquid. The particles are deposited in this on a grating of defined surface division and, following morphological classification, they are counted under the microscope per surface unit and extrapolated to 1 ml of urine.
It is known that cell losses of up to 40% occur during centrifugation, particularly in the case of epithelial cells.
The decanting-off is also associated with considerable errors, since the techniques required for this demand a certain manual dexterity.